怎么算已知a/b=2,求(a*a-ab b*b)/(a*a b*b)

问题描述:

怎么算已知a/b=2,求(a*a-ab b*b)/(a*a b*b)

a/b=2
a=2b
(a*a-ab+ b*b)/(a*a+ b*b)
=(4b^-2b^+b^2)/(4b^2+b^2)
=3/5